How to tell if my thermostat is dying

[babak]

My car heats up really really slowly when it is colder outside. Sometimes (under -10 C) it wont even reach operating temp during my commute to work (~15 miles). Is this normal? Can I check if my thermostat might be on its way out somehow?

Also the temp gauge inside the car (which reads the outside temperature) seems to be over-reading by a few degrees - could this have any relation to thermostat / slower warming up?

I love my car but its a real PITA in winter with no heated seats and this slow warm-up. I feel like I'm driving a refrigerator all winter.

 

[Jon_G]

I can only compare against mine, but a couple of years ago we had a very hard winter here in the UK. I was surprised how long it took my car to fully warm up when setting out at around -10C, probably at least 15 miles. I was concerned about the thermostat, but left in alone... nothing now suggests that it is faulty.

An easy test - if your radiator hoses are becoming warm well before the engine reaches operating temperature then the thermostat is failing to close properly and should be replaced.

Gauge showing outside temperature is unconnected to the thermostat.

The manual for my 2005 i-CTDi clearly describes a neat system where the air conditioning will operate "in reverse" on cold mornings to get hot air blowing from the ventilation well before the engine warms up. But I've never noticed it actually working on mine!

 

[gamble]

Since the days have become colder I have noticed this too. The thrermostat won't move until a good few minutes into the journey (will time how long the next time this happens). Also i notice the exhaust smoking like thomas the tank engine when the stat needle is "stuck" and stone cold

Could this just be a design quirk if it is so common? Or something more serious

 

[brodziu]

if you want your car to warm up quicker in cold days you can partly or fully cover your radiator by some cardboard on the grille, outside temp gauge can be adjusted, but I can't remember now how to do it, but it's clearly described in manuals book

 

[Jon_G]

I think a lengthy warm-up is to be expected - this engine is a large thermal mass plus a lot of oil and coolant. That's why Honda fitted it with the reversable aircon (and not on the petrol models).